Update the Makefile and build directions for in-tree build,
and add Meson build infrastructure. Also convert the ad-hoc
test target into a TAP test.
Currently, the Make build system will not build pg_bsd_indent
by default, while the Meson system will. Both will test it
during "make check-world" or "ninja test". Neither will install
it automatically. (We might change some of these decisions later.)
Also fix a few portability nits noted during early testing.
Also, exclude pg_bsd_indent from pgindent's purview; at least for
now, we'll leave it formatted similarly to the FreeBSD original.
Tom Lane and Andres Freund
Discussion: https://postgr.es/m/3935719.1675967430@sss.pgh.pa.us
Discussion: https://postgr.es/m/20200812223409.6di3y2qsnvynao7a@alap3.anarazel.de
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